Mutations in a new gene, encoding a zinc-finger protein, cause tricho-rhino-phalangeal syndrome type I

Tricho-rhino-phalangeal syndrome type I (TRPS I, MIM 190350) is a malformat ion syndrome characterized by craniofacial and skeletal abnormalities and i s inherited in an autosomal dominant manner(1). TRPS I patients have sparse scalp hair, a bulbous tip of the nose, a long flat philtrum, a thin upper vermilion border and protruding ears. Skeletal abnormalities include cone-s haped epiphyses at the phalanges, hip malformations and short stature. We a ssigned TRPS1 to human chromosome 8q24. It maps proximal of EXT1, which is affected in a subgroup of patients with multiple cartilaginous exostoses an d deleted in all patients with TRPS type II (TRPS II, or Langer-Giedion syn drome, MIM 150230; refs 2-5). We have positionally cloned a gene that spans the chromosomal breakpoint of two patients with TRPS I and is deleted in f ive patients with TRPS I and an interstitial deletion(4,6). Northern-blot a nalyses revealed transcripts of 7 and 10.5 kb. TRPS1 has seven exons and an ORF of 3.843 bp. The predicted protein sequence has two potential nuclear localization signals and an unusual combination of different zinc-finger mo tifs, including IKAROS-like and GATA-binding sequences. We identified six d ifferent nonsense mutations in ten unrelated patients. Our findings suggest that haploinsufficiency for this putative transcription factor causes TRPS I.